Saturday science subject: Alien atmospheres

— 5:46 PM on June 13, 2009

We may soon be able to detect Earth-like planets outside of our solar system, but if we do, how will we know whether their atmospheres have the right ingredients for life? New research actually promises to make that process fairly straightforward. ScienceDaily has more:

When a planet passes in front of its parent star, part of the starlight passes through the planet's atmosphere and contains information about the constituents of the atmosphere, providing vital information about the planet itself. This is called a transmission spectrum and even though astronomers can't use exactly the same method to look at the Earth's atmosphere, they were able to gain a spectrum of our planet by observing light reflected from the Moon towards the Earth during a lunar eclipse. This is the first time the transmission spectrum of the Earth has been measured.

The spectrum not only contained signs of life but these signs were unmistakably strong. It also contained unexpected molecular bands and the signature of the earth ionosphere.

According to Enric Palle of the Instituto de Astrofisica de Canarias, whose team discovered the process, "Now we know what the transmission spectrum of a inhabited planet looks like, we have a much better idea of how to find and recognize Earth like planets outside our solar system where life may be thriving." Palle added that studying the spectrum is a "very effective way" to learn about a planet's biological processes.

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